The enclosed shaft system of the present invention provides in a unified structure, including a unique arrangement of bearings and an impeller-distributor to create continuous circulation of fluid lubricant among all bearing surfaces, wherein one or more journal bearings stabilize shaft movement and permit the flow of lubricant. The invention further includes appropriate seals to contain lubricant within the shaft enclosure and exclude seawater there from and an isolator designed to cooperate with the remaining components and to provide long life with stable characteristics.
A problem with current draft shaft propulsion systems is the protrusion of a rotating shaft through the hull of a marine vessel. The exposure of the shaft to the marine environment requires a large amount of maintenance in order to prevent marine growth from coating the shaft. Marine growth is one of the greatest deterrents to proper and efficient performance of a marine vessel. Marine growth is typically of the animal type, acorn barnacles and tubeworms being the most prevalent. The growth causes excessive turbulence along the shaft, thereby reducing the efficiency of the vessel and associated propeller. The rotation of the shaft further imparting turbulence onto the propeller resulting in vibrations that is difficult to eliminate. The cleaning of an exposed propeller shaft is difficult due to its shape and the need to perform most such cleaning while the vessel is in the water.